The secure joining of wheel disks, brake disks or the like and an axle that is rotatably supported on a rail vehicle in the installed state is of the utmost importance for the reliable operation of the latter. Since the wheels are mostly fixed on the axle by means of a frictional engagement only, an interference fit needs to be produced between the wheel bore and the outside diameter of the axle. The installation of new or reconditioned wheel disks, brake disks or the like on the axle, as well as their removal from the axle after the wear limit is reached, requires high forces on the order of 800 to 2500 kN.
In the following description, the term “wheelset” refers to the axle with all components to be pressed thereon such as wheel disks, brake disks or the like. The term “joining” refers to the assembly of the components or, in other words, pressing the wheel disks, brake disks or the like on the axle, as well as pulling these components off the axle.
Hydraulic presses have the ability to exert high forces over long strokes and therefore are optimally suited for joining wheelsets. Hydraulically operated wheelset presses already were successfully used toward the end of the nineteenth century. With respect to their basic design and their function, wheelset presses known so far essentially correspond to one another and to those used toward the end of the nineteenth century. As an example, we refer to the wheelset press Series PR of the firm Hoesch Maschinenfabrik Deutschland AG. This wheelset press is realized in the form of a horizontally arranged two-column press with a high-pressure cylinder that is driven by hydraulic oil. The high-pressure cylinder is installed in a lateral cylinder beam, in which both columns are also fixed with one end. The other ends of the columns are supported by an end beam that—analogo us to the cylinder beam—is provided with a flange to mount the wheelset press on the floor. The upper ends of the cylinder beam and the end beam frequently carry a bridge crane arrangement that extends essentially parallel to the columns.
Both columns are rotatably supported in the cylinder beam and in the end beam and respectively feature a spindle thread over their free length between the cylinder beam and the end beam. This thread makes it possible to displace a C-shaped traveling beam that serves as abutment and features rotatable nuts with internal threads that are engaged with the spindle threads of the columns. The traveling beam features grooves, into which the actual joining tools that are open toward the front can be inserted.
To join a wheelset by means of this wheelset press, the axle and the component to be joined are initially transferred into the pre-assembly position with the aid of the bridge crane. In this position, the component to be joined is pushed on the axle and arranged such that it can be pressed onto a peripheral collar that forms the interference fit. Subsequently, the axle is manually aligned—while being suspended on the bridge crane—such that its central longitudinal axis and the central longitudinal axis of the press cylinder coincide. In this position, one end of the axle is fixed by means of a spring-loaded centering point that is arranged on the face of the pressure piston of the high-pressure cylinder and engages into a centering bore of the axle while the other end of the axle is fixed by means of a second centering point that can be moved with the aid of a hydraulic cylinder mounted, for example, on the end beam. Before the axle is fixed in position, the traveling beam is displaced in such a way that the tool inserted therein is situated behind the component to be joined referred to the pressing direction.
Subsequently, the actual pressing process is initiated by actuating the high-pressure cylinder to displace the axle in the pressing direction until the component supported on the tool is situated in the desired position on the axle.
To join another component, the axle is then removed from the wheel press by means of the bridge crane and the next component is transferred into its pre-assembly position when pressing on a component or the loosened component is removed when pulling off a component. Subsequently, the tool is moved into the position required for the next pressing process by rotating the nuts provided with threads. The axle with the components is then transferred into the above-described pressing position by the operating personnel—namely once again with the aid of the bridge crane—and the joining process is carried out anew.
In another known wheelset press, the actual press cylinder is installed in the cylinder beam that is connected to the so-called traveling beam, e.g., by means of two round columns, wherein the traveling beam fulfills the function of the abutment and accordingly is supported on the columns in a longitudinally displaceable fashion. It can be locked in several positions with the aid of recesses in the form of round grooves on the columns. This basic design has barely changed over the course of the last hundred years. In North America, in particular, rectangular tie rods are used instead of the round columns, wherein the locking is realized by means of a bolt in these tie rods.
In devices of this type, it is disadvantageous that the wheelset needs to be placed into the wheelset press and removed again several times with the aid of the bridge crane before all joining processes are completed, namely because this drastically increases the costs for joining wheelsets due to the required personnel. Since the components can be extremely heavy and are manually placed into the wheelset press, the risk of injuries to the operating personnel also should not be underestimated.
One decisive additional development of the traditional basic design was the fully automated wheelset press disclosed by the applicant in EP 1 201 350 B1 wherein the press frame is composed of vertical press beams and horizontal connection columns. The significant innovation of this wheelset press was that the U-shaped opening in the traveling beam was so large that the traveling beam could be displaced into all press positions over an entire wheelset fixed between the centering points, wherein the actual pressing tool was transferred on the traveling beam from a pressing position into a displacing position transverse to the axial direction for this purpose. This made it possible to significantly reduce the cycle times. In contrast to traditional solutions, however, the width of the U-shaped opening in the traveling beam needs to be significantly increased to displace the beam over all wheelset components. Consequently, the “basic insert” that serves as a receptacle for the actual pressing tool and can be transversely displaced is substantially larger than in traditional solutions. An upper and a lower connecting beam absorb the longitudinal forces between the cylinder beams on the ends, wherein the lower connecting beam is arranged below the floor such that its upper side ends flush with the floor. Keys are installed in the traveling beam and can be inserted into the lower and the upper connecting beam in the respectively desired pressing position to fix the traveling beam in the pressing position. The prior art only shows a type of press frame which is composed of cylinders or press beams and horizontal columns that are connected to one another.